This invention relates generally to manufacturing of surface mount electronic components including magnetic cores, and more specifically to manufacturing of surface mount inductors.
Manufacturing processes for electrical components have been scrutinized as a way to reduce costs in the highly competitive electronics manufacturing business. Reduction of manufacturing costs are particularly desirable when the components being manufactured are low cost, high volume components. In a high volume component, any reduction in manufacturing costs is, of course, significant. Manufacturing costs as used herein refers to material cost and labor costs, and reduction in manufacturing costs is beneficial to consumers and manufacturers alike.
A variety of electrical components such as transformers and inductors include at least one winding disposed about a magnetic core. For example, at least one type of inductor includes a conductive wire coil wrapped around a toroid-shaped ferromagnetic core, and each end of the coil includes a lead for coupling the inductor to an electronic circuit. As the size of the component is reduced, and especially for surface mount components, the coil leads can be fragile and difficult to connect to a circuit. Therefore, in one type of inductor, for example, a header assembly is adhesively bonded to the core and the coil leads are wrapped about terminals of the header assembly to facilitate connection of the coils to external circuitry. Aside from the time and cost involved of applying and curing the adhesive, the adhesive bond generates stress in the core, which reduces magnetic permeability of the core and degrades desirable properties of the core in use. While reduced magnetic permeability of the core may be mitigated by adding additional turns of the coil to compensate for the affected properties of the core, this is not an efficient solution from a manufacturing standpoint.
Still further, when automated equipment is used to install the component, such as in surface mount applications, additional external components are typically employed to protect the coil leads and termination assemblies during handling by automated equipment. These components further add to manufacturing costs.
In one aspect, a core assembly for a surface mount electronic component is provided. The core assembly comprises a core fabricated from a magnetic permeable material, and at least one conductive coil termination embedded within said core.
In another aspect, a surface mount electrical component is provided. The electrical component comprises a ferromagnetic core comprising at least one integral conductive coil termination, and a coil wound around said core. The coil comprises at least one lead and the lead is coupled to said at least one conductive termination.
In another aspect, a surface mount electrical component is provided. The component comprises a ferromagnetic core comprising an opening therein and at least one integral conductive coil termination pre-formed into said core, a coil wound around said core, and a pliable plug extending from said core and comprising a flat upper surface forming an engagement surface for surface mount technology equipment. The coil comprises at least one lead coupled to said at least one conductive coil termination.
In another aspect, a method for assembling a surface mount electrical component including a core and coil wound about the core is provided. The method comprises providing a core including at least one integral coil termination pre-formed therein, winding the coil about the core, and attaching the at least one lead to the at least one coil termination.
In still another aspect, a method of mounting a surface mount electrical component including a core and a coil wound about the core is provided. The method comprises providing a core including first and second coil terminations pre-formed therein, winding the coil about the core, the coil including first and second leads, attaching the first coil lead to the first coil termination, attaching the second coil lead to the second coil termination, and coupling a pliable plug to the core. The plug comprises a flat outer surface, and using the flat outer surface of the plug, the conductive coil terminations are positioned in contact with conductive portions of a printed circuit board to surface mount the electrical component to the board, thereby establishing an electrical connection through the coil.
In an exemplary embodiment of the invention, a toroid core and coil assembly includes coil terminations integrally formed into the core for facilitating quick and relatively simple connection of the coil leads without external components and associated adhesive bonding processes. The terminations include contoured surfaces to guide coil leads and facilitate connection of the leads to the terminations. Stress on the core which degrades desired magnetic properties is therefore substantially avoided, together with associated additional coil turns to compensate for degraded properties, thereby further reducing manufacturing costs. In addition, the core and coil assembly is easily accommodated by automated equipment by insertion of a pliable plug including a flat surface that facilitates vacuum pick up with surface mount technology assembly equipment.